Rotary mercury vacuum-pump.



H. A. FLEUSS.

ROTARY MERGURY VACUUM PUMP.

APPLICATION FILED JUNE 1,1909.

Patented Feb. 1, 1910.

2 SHEETS-$111131 1.

m H. A. FLEUSS. ROTARY MERCURY VAOUUM PUMP.

APPLICATION FILED JUNE 1,1909.

Patented Feb. 1,1910.

2 SHEETS-SHEET 2.

HENRY ALBERT FLEUSS, OF READING, ENGLAND.

ROTARY MERCURY VACUUM-PUMP.

Specification of Letters Patent.

Application filed June 1, 1909.

Patented ltcb. I, 191M)... Serial No. 499,431.

To all whom it may concern:

Be it known that I, HENRY ALBERT hLnUss, engineer, a subject of the King of Great Britain, residing at 14-7 London road, Reading, Berkshire, England, have invented new and useful Improvements in Rotary Mercury Vacuum-Pumps, of which the following is a specification.

This invention relates to vacuum pumps in which spaces or channels within a drum more than half immersed in mercury are as the drum is revolved alternately filled with mercury and with air.

According to this invention I form these spaces entirely within the rim of the drum which I make perfectly cylindrical both on its inner and outer circumference. The inlet to and outlet from each space I form one through the inner circumference of the rim at one side of the drum and the other through the outer circumference 011 the opposite side. Thus the inlet by which air and mercury enter alternately into each space and the outlet by which air and mercury leave this space can both be made of large area and yet the change from being open to air or to mercury be effected rapidly as the drum is rotated. As also both the inner and the outer circumference of the rim of the drum is made perfectly cylindrical without any projection extending either inward or outward from it the extent to which the mercury is disturbed when the drum is revolved is reduced to a minimum.

The rim of the drum I form of two concentric cylinders one within the other with a space between them. At two opposite points of the circumference of these cylinders are inclined partitions carried across the space between them. An opening is made through the outer cylinder on one side of each partition and another opening is made through the inner cylinder on the 0pposite side of each partition. The space between the two cylinders is thus formed into two channels each of which at its inner end is open to the interior of the inner cylinder and at its outer end is open to the space around the exterior of the outer cylinder. The ends of the two concentric cylinders are secured airtight to end disks. One disk is secured to the end of a driven shaft which extends out through one end of the fixed outer casing. The other disk has a concentric hollow tubular projection extending from it through which the mercury in which the lower part of the exterior of the drum is immersed can pass freely into the interior of the inner cylinder.

The tubular projection h is provided in order that if any air should be clinging to the outer surface of the end of the drum and be carried down by it below the surface of the mercury it may if it becomes detached travel upward along the surface of this end and if it encounters the tubular projection may pass upward around it and not enter into the interior of the drum.

A pipe carried through the outer casing is passed through the hollow tubular projection and made to extend upward into the space above the mercury in the interior of the inner cylinder. On the exterior of the casing the pipe may be connected to the vessel to be exhausted while the space in the interior of the outer casing above the mercury is connected with a secondary air pump.

When the drum is rotated the inner end of each channel is in turn brought below the surface of the mercury in the interior of the drum and as the drum continues to rotate the channel fills with mercury while the air previously contained in the channel is driven out from its outer end. When by the continued rotation of the drum the outer end of the channel is brought below the surface of the mercury outside the drum. the mercury with which the channel is then filled is as the drum continues to rotate delivered from the channel through its outer end and the mercury thus passing outward from the outer ends of the channels can always flow back freely and quietly to the interior of the drum through the drums hollow trunnion the passage through which may be of large area.

By making the channels which are to be alternately filled with air and with mercury of uniform area throughout their length and by making the openings at their ends of the same area as the channels themselves very little disturbance of the mercury is caused by the emptying and filling of the channels and as the inner as well as the outer circumference of the drum is made perfectly cylindrical the disturbance of the mercury caused by the rotation of the drum is reduced to a minimum and the drum can be rotated at a higher speed than was practicable with pumps of this kind as heretofore constructed.

Figure 1 is a vertical section of the pump.

Fig. 2 is a section of the cover of the outer casing. Fig. 3 is a transverse section of the revolving drum. Fig. i is an end View of the lower part of the outer casing.

a is the outer casing closed by a top cover 6. c a spindle passed through a stuifing box extending from one end of the casing. cl a circular disk keyed onto the inner end of the spindle. This disk forms one end of the revolving drum of the pump. To it is secured one end of a concentric inner cylinder 6 and outer cylinder f, the joints being smeared with a jointing compound to form an airtight joint. The opposite ends of .these cylinders have similarly secured to them a disk 9 which at its center has a short hollow tubular projection h extending from it which is open at its end and immersed in the mercury contained in the outer casing a.

To insure that the tubular projection shall always be well immersed in the mercury I mount the casing and the driving spindle at an angle to the horizontal as shown at Fig. 1. This admits of the passage through the tubular projection being made of large diameter.

w is a stop on the casing a to prevent the drum from slipping off the spindle.

The vessel to be exhausted is connected through cock i with pipe having a branch pipe k extending from it which passes through the center of the end of the outer casing and through the tubular projection h to the upper part of the interior of the inner cylinder 6.

The inner and outer cylinders forming the circumference of the revolving drum may be cut from a single cylinder or casting of steel. The inner and outer circumference of this cylinder may be turned truly in a lathe, the concentric portions of the cuts which are to divide the inner portion from the outer portion of the cylinder may also be made in the lathe while the ends of the cuts may be made by a revolving cutting tool or the lathe might be adapted to make the inclined ends of the cuts as well as its concentric portions. When the cut is completed one half of the inner portion of the cylinder will be in one piece with one half of the outer portion of the cylinder as shown in Fig. 3. These two parts are afterward secured as shown in Fig. 1 to the two disks (1 and g which form the ends of the revolving drum. All parts of the drum can thus readily be shaped to form by ordinary cutting machinery and can therefore be .made at small cost.

To reduce the amount of mercury required to be filled into the casing a a displacing block Z may be made to surround the central boss of the disk 61 and be formed with ball bearings so that the boss may turn freely within it. The block l may itself be restrained from turning by pins m projecting from it and coming one on one side and the other on the opposite side of the fixed pipe 70.

a (see Fig. 2) is an opening through the top cover 6 of the casing a through which mercury can be filled into the casing. It can be closed by a screw cap 0 and the joint be kept covered with mercury contained in a surrounding cup p.'

g is a screw plug screwing into one end of the casing. When filling mercury into the casing the screw plug is taken away and mercury supplied to the casing through the cup p until the casing is filled up to the level of the dotted line 1, 2 in Fig. 1 when it will commence to overflow through the opening from which the screw plug 9 has been taken away. The screw plug 9 can then be screwed back into place and secured airtight.

7' is a pipe led away from the top cover 7) of the casing to a secondary air pump which may be of any ordinary construction. A vacuum gage may be connected to this pipe at 2. Should mercury from any cause find its way into the lower part of the pipe 7' and its branch pipe 7.: it can be drawn oil by unscrewing the screw cap 8 which closes the lower end of a downward extension of the pipe As the cap is unscrewed all mercury flowing out from the extension of the pipe j can be collected in the cup i.

If the drum be revolved in the direction of the arrow in Fig. 3 the inner end of each of the passages in its circumference as it comes above the level of the mercury is open for air to enter into it from the upper air space in the interior of the drum and fills with air until this end of the passage is again caused to dip into the mercury. Shortly after it does so the opposite end of the passage rises above the level of the mercury in the outer casing and all air previously contained in the passage is delivered outside the drum into the casing from which it is continuously drawn off by the action of the secondary pump.

lVhat I claim is 1. In a rotary mercury vacuum pump the combination of an outer casing partly filled with mercury, a shaft passing through one end of this casing, a drum concentric with this shaft and having one of its ends fixed on the inner end of the shaft and a central opening formed through its opposite end which opening is always covered with mer cury the drum also having the inner and outer circumferences of its rim truly cylindrical with no projection extending either inward or outward from them and two channels formed in this rim, each extending half way around it and one end of each of which opens through the rims inner circumference and the other end of its outer circumference, a pipe led through the central opening in the end of the drum and extending upward to the upper part of its interior, a pipe extending from the upper part of the outer casing and one of these pipes connected with the vessel to be exhausted.

2. In a rotary mercury vacuum pump the combination of an outer casing partly filled with mercury, a shaft inclined to the horizontal passing through one end of this casing which is similarly inclined to the vertical, a drum concentric with this shaft and having one of its ends fixed on the inner end of the shaft and a central opening formed through its opposite end which opening is always covered with mercury the drum also having the inner and outer circumferences of its rim truly cylindrical with no projection extending either inward or outward from them and two channels formed in this rim, each extending half way around it and one end of each of which opens through the rims inner circumference and the other end through its outer circumference, a pipe led through the central openmg in the end or the drum and extendlng upward to the upper part of its interior, a-

pipe extending from the upper part of the outer casing and one of these pipes connected with the vessel to be exhausted.

3. A rotary mercury vacuum pump in which the revolving portion which is more than half immersed in the mercury consists of drum the inner and outer circumferences of whose rim are both truly cylindrical with no projection extending either inward or outward from them while the rim itself has two channels formed within it which at their inner ends open through the riins inner circumference and at their outer ends through the rims outer circumference.

HENRY ALBERT FLE USS.

Witnesses H. D. JAMESON, F. L. RAND. 

